1. Field of the Invention
The present invention relates to a liquid crystal display. More particularly, the present invention relates to a liquid crystal display in which brightness of a light emitting diode is changed according to regions of a screen.
2. Description of the Related Art
A liquid crystal display (LCD) comprises an LCD panel having a thin film transistor (TFT) substrate on which the TFTs are formed and a color filter substrate on which the color filters are formed, and a liquid crystal layer disposed therebetween. Since the LCD panel does not emit light by itself, the LCD may further comprise a backlight unit in the rear of the TFT substrate as a light source for providing light. The transmittance of the light generated from the backlight unit is adjusted according to an alignment of the liquid crystal in the liquid crystal layer.
The light source of the backlight unit may be a cold cathode fluorescent lamp (CCFL), an external electrode fluorescent lamp (EEFL), organic light emitting diode (OLED), and the like. Recently, a light emitting diode (LED) having a good color reproducibility and brightness has become popular.
In general, the LED provides light having a constant strength for the LCD panel, without relation to an image displayed on the screen. Hence, if a dark image is displayed on the screen, the light of the LED leaks. Thus, the contrast ratio is poor and consumption power is used wastefully.
Recently, a method has been developed in which the screen is divided into a plurality of regions and thus, the LED can have different brightness according to the region. If such a method is used, the bright screen is brighter and the dark screen is darker. Accordingly, the display quality can be improved. However, control of the brightness is difficult since the light of the LED influences other adjacent regions.
Accordingly, a need exists for a system and method in which brightness of a light emitting diode is changed according to the regions of a divided screen.